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Oreshak: old village, environs, nature
about our village
Oreshak

choosing a settling place in Varna region
the chronicle:
choosing a settling place
in Varna region

     

Light effectiveness of photosynthesis and economical lighting for plants

hypothesis:
Photosynthesis was adapted to radiant energy of the red light, to feeble sunlight in conditions of the ancient heavy atmosphere.
practice:
Lighting for plants by red ultra-bright LEDs (ultra bright light emitting diodes).

Photosynthesis efficiency by light wavelength (or light colour)

All the food we eat,
wood we build with,
and fossil fuels we use
are products of photosynthesis.

Vermass, Wim.
An Introduction to Photosynthesis and Its Applications.
Arizona State University. Retrieved on 2007-09-29.


And all the oxygen too?
Envirociety.org

Visible light (or visible radiation, or electromagnetic waves) band is the region in electromagnetic spectrum from 400 nm (nanometre) to 700 nm. Flora is using light via photosynthesis process. Photosynthetically active radiation curve (PAR) is the graph of the photosynthesis efficiency by light wavelength (or "light color").

Main minimum of the photosynthesis efficiency locates in the green light region of spectrum.
Main maximum of the photosynthesis efficiency locates in the red light region.

Figure 1.
Light colour and photosynthesis efficiency
(approximate graph).

Figure 1. Light colour and photosynthesis efficiency graph.
 

 

PAR-curve, white and red light illuminance, power of the white and red light illuminance

Figure 2.
Illuminance and power: white (or sunlight) lighting and red lighting.
PAR (Photosynthetically Active Radiation).

Figure 2. Illuminance and power: white (or sunlight) lighting and red lighting. PAR (Photosynthetically Active Radiation).
 

General idea of the effective illuminance for photosynthesis:

Red illuminance (Ir on Figure 2) < white illuminance (Iw) for equal photosynthesis effects,
because
mean value of the photosynthetic efficiency of red band light (PHSr) > mean value of the photosynthetic efficiency of white light (PHSw).

Therefore
power of the red band light (Pr) < power of the white light (Pw) for equal photosynthesis effects.
Additional cause:
It's required less energy for red lighting then for white lighting (for equal red illuminance and white illuminance).

 

Application of red lighting for agriculture.

Lighting by red ultra bright light emitting diodes (LED):
LED`s lifetime: >50000 hours (or eternity);
Luminous efficacy: >70 lumens per watt.

Compare:
Lighting by ordinary electric-light bulb:
lifetime: 750 hours;
Energy efficiency: 11 lumens per watt (warm white colour).
Maybe the photosynthetic efficiency of incandescent lamp (by input power) is lower (>20 times), then the photosynthetic efficiency of red lighting diode.
Additional factor:
A incandescent light bulb emits hurtful (for flora) infrared electromagnetic radiation.

  >> More articles - part Economical eco building and engineering  

 
 
     
>> How we use "free energy" from renewable sources
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building of the underground heat accumulator

 
 
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